Automatic shotgun choke



INVENTOR.

Aim/ways.

April 28, 1959 A. E. SCHROEDER AUTOMATIC SHOTGUN CHOKE Filed Jan. 25,1956 Ar/a' Jab/v60???" BY United States Patent AUTOMATIC SHOTGUN CHOKEArlo E. Schroeder, Newton, Kans. Application January 25, 1956, SerialNo. 561,263 Claims. (Cl. 42-79 This invention relates to new and usefulimprovements in shotguns, and has particular reference to the devicesused in connection with shotguns and commonly designated as chokes,which are devices used to reduce the area of the shot pattern of thegun.

The principal object of the present invention is the provision of achoke which is adjustable from an unrestricted or open-choke setting toa relatively restricted or full-choke setting, and which will advancefrom said open-choke setting to said full-choke setting automaticallyafter the gun is fired. In firing at birds or other moving targets whichnormally move farther away from the gunner if not hit by the first shot,it is desirable that the choke be restricted on successive shots,whereby to reduce the shot pattern so that it will retain itseffectiveness and hitting power at greater distances. The adjustmentmust be automatic and rapid, since the gunner commonly does not havesutficient time in which to make the adjustment manually. It will beobvious that the full-choke setting referred to above is relative only,and may if desired actually be on intermediate or modified choke.

Another object is the provision of an automatc shotgun choke of thecharacter descrbed wheren the adjustment is accomplished automaticallyby the force of recoil when the gun is fired.

A further object is the provision of an automatic shotgun choke of thecharacter described which may be moved manually to either settingdesired, and locked in either of said settings in the event automaticoperation v is not desired.

Other objects are extreme simplicity and economy of construction,efliciency and dependability of operation,

. and adaptability for use with shotguns of virtually any chokeposition,

Fig. 3 is a fragmentary view similar to Fig. 2, show ing the choke inthe full-choke position, and

Fig. 4 is a sectional view taken on line IVIV of Fig.- 2.

Like reference numerals apply to similar parts throughout the severalviews, and the numeral 2 applies to the barrel of a shotgun, only theforward end portion of said barrel being shown. The choke mechanism,designated generally by the numeral 4, is mounted at the forward end ofsaid barrel. Said choke mechanism incorporates a cylindrical tubularbody 6 which is disposed coaxially with and forms a forward extension ofbarrel. The rearward end portion 8 of said body member is enlarged andinternally threaded for connection with body shoulder 18 and notch 33formed in block threads formed externally on the barrel, said threadedconnection being designated at 10. Obviously a soldered or otherpermanent or detachable rigid connection could be used instead of thethreads if desired.

The forward end portion of the choke body has a plurality of slits 12formed longitudinally therein at regularly spaced circumferentialintervals, thereby forming a plurality of longitudinally projectingtongues 14. The

material of the body member is sufliciently resilient that said tonguesmay be deflected inwardly, as will be described, to restrict thediameter of the forward end portion of the body member. desiredyieldaliility of the tongues, the body member may be weakened at thebase of said tongues by grooving the body member peripherally, as at 16.

Adjacent its rearward end, body member 6 is provided with an externalperipheral shoulder 18, whereby the diameter of said body member isincreased. Threaded or otherwise fixed to said portion of increaseddiameter is the rearward end of a housing tube 20, said housing formingan annular chamber 22 therebetween. Said housing extends flush with theforward end of the body,

and is provided at its forward end with an internal peripheral flange24, the inner edge of said flange engaging tongues 14 of the body intheir normal or expanded position, whereby to limit their outward move,-ment. Body member 6 is provided adjacent its forward end with anexternal, rearwardly facing bevelled shoulder 26 extending peripherallytherearound. Said shoulder is of course carried by the tongued portionof the body, but is disposed in rearwardly spaced relation from housingflange 24.

An inertia block 28 having the form of a cylindrical tube is disposed inannular chamber 22, having sliding engagement both with body member 6and housing 20, and is normally disposed between shoulders 18 and 26 ofthe body member. It is provided at its forward end with a peripheral camface 30 bevelled correspondingly to shoulder 26 of the body member, saidshoulder acting as a cooperating cam member. Said bevelled face is urgedtoward said shoulder by a coil spring 32 disposed in annular chamber 22behind inertia block 28 and urging said block forwardly, said springbearing at its rearward end against shoulder 18 and at its forward endagainst a shoulder 34 formed externally on the inertia block. Saidspring is also maintained in torsional stress as will appear, theextreme end portions 29 of said spring being bent to extend parallel tothe axis of the spring and being retained respectively in a notch 31formed in shoulder 34.

A short latch pin 36 is threaded fixedly in inertia block 28, andextends radially downwardly therefrom through a cooperating latch slot38 formed longitudinally in housing 20. Said slot is provided at oneside thereof with a pair of lateral notches 40 and 42 into which pin 36may be moved, notch 42 being disposed at the extreme forward end of slot38 so as to receive pin 36 when inertia block 28 is in its extremeforward or choking position, and notch 40 being disposed rearwardly fromnotch 42 so as to receive pin 36 when block 28 is sufliciently far toshoulder 26. At the side of slot 38 opposite notches 40 and 42, slot 38is provided with a third lateral notch 41 adapted to receive pin 36. Theforward edge of notch 41 is notched forwardly to form a rearwardlyopening socket 43 which serves to prevent angular movement of pin 36when said pin is disposed therein. The rearward edge of notch 41 isbevelled as at 45. Spring 32 is tensioned so as to urge inertia block 28rotatively' in a counter-clockwise direction, looking forwardly so as toPatented Apr. 28, 1959 If necessary to provide the aesspsa urge. pin 36?toward the side of slot 38 having notches 40 and 42 formed therein.

The operation of the choke is substantially as follows: Assuming firstthat latch pin 36 has been manually moved into. notch 41 and. forwardlyinto.- socket. 43 thereof, the parts then have the position shown. inFig, 2. Sincecam face 30 of inertia block 28 is. disposed. rearwardly ofcam shoulder 26 of. the body member, body member tongues 14 are expandedby their own. resilience to their open-choke position. Pin 36. isprevented from being twisted out of notch 41. into slot. 38. by thetorsion of spring 32, due to. the. inclusion. of. said pin in socket 43of. notch 41.

When the gun isv fired, the gun. and choke of course recoil sharply,and. the. choke housing, acting on latch pin. 3.6, forces. inertiablock: 28 to. travel rearwardlly with.

the. choke body. Thus the cams 26i-30. cannot. operate: on directrecoil. This delay of. the cam. action isv essen.-- tial since therecoil movement begins before the charge of. shot reaches. the end ofthe barrel, and direct action of. the. cams would result. in choking ofthe gun even on. the first shot. When the recoil of the gun is stopped,orat. least. retarded, by the gunners shoulder, inertia block 28.continues tomove rearwardly by its ownv momentum, compressing. spring32. The rearward movement of said block disengages pin 36 from socket 43of. notch 41,. and causes said pin to impinge sharply on the bevelledrear- Ward edge 45 of the notch. Said bevel acts. as a cam, forcing saidpin outwardly from notch 41 into slot 38. The positive action ofbevel 45is also assisted by the torsional tension of spring 32, which tends toturn said pin into slot 38. Said spring also serves to. hold. said pinin slot. 38, preventing: any possibility that, said. pin might. re enternotch 41 on. forward movement; of the inertia block. Said. inertia blockis forced forwardly by spring 32. after said spring has absorbed the.momentum-of the; block. During the forward movement of the block, pin 36by-passes notch 41, permitting engagement of cam face 30. of the. blockwith. cam shoulder 26 of the body, said block. overriding said. shoulderthereby contracting tongues 14 inwardly to their full-choke? position,the parts then having the position shown in. Fig. 3. By the time cams26-30 function, the. recoil is completed and the. charge has cleared theend. ofthe choke and there is no danger of operating the chokeprematurely. In this sense, it may be said that the latch. means,though. recoil operated, incorporates a time-delay actionprevent. ingoperation of the cams tillv the recoil has. been. completed.

During. the. forward, movement of pin 36,, it. moves with sufficientspeed that: it' by-passes and doesnot enter notch.- 40, despite thetorsional. stress of' spring 32. However, to prevent battering. of the;forward edge of. notch. 40 by the. pin, the. tongue of. metaL 47between. notches 40 and 42' may be. shortened, as clearly shown. inFig.1.. Body flange 24 arrests the forward movement of. the block, andspring. 32 immediately functions to turn. pin 36 into notch 42, thereby.locking the. choke. in its re-- stricted position. On all subsequentshots, therefore, the

choke will remain. in itsv restricted. position, until such.

time. as pin 36.. is.manually'moyed.intosocketr43. of. notch 41.Also,.the choke may be. locked in its. open position by moving pin 36manually. intonotch 40,v and will re.- main open through any number ofshots. Pin 36 may of course be moved into either of. the. lockingnotches. 40 or 42 at. any time. desired, and. will. be; retainedtherein. by. spring; 32.

Housing 26 acts: as a; guide. for the: inertia. block, in. suring;straight:v travel. of". said. centering; thereof relative to bodyshoulder 26. also. permits the. in.

terchangeableuse. in. the choke. of inertia blocks; off-differ. entinternal diameters. of the degree of barrel restriction actuallyprovided. by

the choke, both in its. relatively; open. and relatively re;--striated.positions.v It: will. besnntedtalso, that the:

This permits ready adjustment.

block is sufli'ciently long to extend rearwardly of the body slits 12,even when said block is in its forwardmost position, thereby in largemeasure preventing leakage of explosion gasses into chamber 22. Thisreduces the danger of fouling the mechanism, and also reduces thefrequency with which the mechanism must be cleaned.

While I have shown and described a specific embodiment of my invention,it will be apparent that many modifications of structure and operationcould be made without departing from. the spirit of: the invention asdefined by the scope of the appended claims.

What I claim as new and desire to protect by Letters Patent. is:

1. An automatic shotgun choke comprising a body member adapted to besecured to a shotgun barrel to form a forward extension thereof, andhaving a resiliently contractile section operable to be restricted toreduce the internal diameter thereof, a tubular housing concentric. withsaid body member, being fixed to a rigid. portion of said body memberand forming an annular chamher around said contractile section, saidhousinghavinga. slot formed longitudinally therein, anv inertia block inthe form of a cylindrical tube; carried in said annularchamber forforward, rearward and rotary movement, said contractile body section andsaid inertia block having cooperating cam surfaces formed thereon andvoperable by forward movement of said inertia block fromv a normal.position to restrict said contractile body section, a spring carried insaid annular chamber and urging said inertia block forwardly, and a pinfixed in said inertia block and, extending radially through said housingslot,

said slot having a side notch formed therein adapted toreceive said pin,the forward wall of said. slot being,

cam said pin transversely into said slot when. said inertia blockrecoils' relative to said. housing.

2. A choke as recited in claim 1 wherein said housingslot. is providedwith. a pair of additional side notches formed. therein, the rearwardedges of said additional notches being disposed in. planes at rightangles to theaxis of the body member, said pin being selectively movableinto either of said notches whereby to lock said inertia block either inits normal position or in a forward position in which saidcontractilebody section. is restricted.

3. An. automatic shotgun choke comprising a body member adapted to besecured to a shotgun barrel. to form a forwardextension thereof,andhaving a resiliently contractile section operable to be restricted toreduce; the. in, ternal diameter thereof, a tubular housing concentric.with. said body member, being fixed to a rigid portion of said bodymember and forming an annular chamber around said contractile. section,said housing, having a slotformed. longitudinally therein, an inertia.block: in the form of; a cylindrical tube carried in said annularchamber for forward, rearward and rotary movement, said contractile bodysection and saidinertia block having cooperating. cam surfaces formedthereon and operable by forward movement: of: said inertia block from anormal position. to restrict said contractile body section, a springcarried. in said annular chamber and. urging said inertia blockforwardly, anda pin fixed in said inertia block and extending radiallythrough said housing slot, said slot having. a side notch formed thereinadapted to receive said pin, the forward. wall of said slot beingsocketedto. prevent transverse moyement' of the. pin when said. pin.positioned.

therein, said inertia. block being: then in its. normal positionlongitudinallyof. the: choke body, and. the rearward.

wall. of. saidnotch being; bevelled whereby tocant said.

pin transversely into said slot when said inertia block reinto said slotwhen said inertia block recoiis relative to said housing.

4. An automatic shotgun choke comprising a body member adapted to beattached to a shotgun barrel to form a forward extension thereof, andhaving a contractile section operable to be restricted to reduce theinternal diameter thereof, an inertia member carried by said body memberfor forward and rearward movement from a normal position relativethereto, said inertia member and said body member having cooperatingactuating members formed thereon and operable by forward movement ofsaid inertia member to restrict said contractile section, resilientmeans urging said inertia member forwardly, a member fixed to said bodymember and having a slot formed therein parallel to the axis of saidbody member, a pin fixed in said inertia member and extendingtransversely through said slot, said slot having a side notch into whichsaid pin may be moved to lock said inertia member in its normal positionagainst forward movement, the forward wall of said notch being socketedto receive said pin to prevent lateral movement thereof into said slot,whereby said inertia member is forced to recoil rearwardly with saidbody member when said gun is fired,

said inertia member continuing to move rearwardly against said resilientmeans by its own momentum after the recoil movement of said body memberis substantially completed, and the rearward wall of said notch beingbevelled, whereby on rearward movement of said inertia member relativeto said body member, said pin will engage said bevelled notch wall andbe cammed thereby into said slot.

5. An automatic shotgun choke as recited in claim 4 wherein saidresilient means, in addition to urging said inertia member forwardly, isalso tensioned to urge said pin transversely out of said notch into saidslot, whereby to assist the cam action of the bevelled wall of saidnotch, and to prevent re-entry of said pin into said notch duringforwardly movement of said inertia member.

References Cited in the file of this patent UNITED STATES PATENTS685,669 Broyles Oct. 29, 1901 1,508,605 Legett et al Sept. 16, 19242,417,721 Whedon Mar. 18, 1947 2,685,144 Schroeder Aug. 3, 19542,759,286 Moore Aug. 21, 1956

